This invention relates generally to alarm systems and more particularly to anti-theft alarm systems for monitoring the disposition of electrical devices of the type normally plugged into a wall A.C. electrical power outlet.
There currently exists a need for a reliable, inexpensive and versatile alarm system for monitoring the disposition of electrical appliances, particularly of the variety which are normally plugged into a wall A.C. electrical power outlet. For example, the motel industry has in recent years experienced a significant increase in vandalism which, to a large extent, has been directed at television receiver's provided by motels for viewing by motel guests. Although various measures have been taken by the motel industry to safeguard television receivers, these efforts have not been altogether satisfactory. For example, various means have been devised to securely fasten the television receiver chassis to other objects whose theft is considered likely. However, various ingenious techniques have been developed to thwart such safeguards. Furthermore, it will be appreciated that the use of security personnel to constantly patrol the typically appreciable extent of motel property is a highly impractical solution to the problem.
In order to provide motel proprietors with some degree of theft protection, there are presently available various types of alarm systems for monitoring unauthorized disturbances of property such as television receivers. For example, means are known in the prior art which attach directly to a television receiver and provide an alarm in response to any unauthorized movement thereof. Devices of this type are generally largely electronic in nature and exhibit various disadvantages in connection with their practical implementation. Among others, these disadvantages include high per unit cost, a rather delicate construction and, frequently, insufficient reliability. Furthermore, prior art alarm systems of the motion responsive type frequently require delicate adjustments and include sensors which do not adequately respond to motion in all directions.
As previously mentioned, prior art alarm systems whose primary purpose is that of protecting relatively easily movable property are most frequently of the type which directly attach to the property under consideration. Therefore, to be useful at all, prior art alarm systems of this variety are normally self-contained units operable from a portable power supply such as one or more batteries, and must be individually associated with each item of property to be protected. These characteristics pose several problems. Initially, there is the problem of reliability associated with battery operated equipment. Either the batteries must be replaced in a regular manner or, alternatively, a maintenance schedule must be established for periodically testing the battery charge. In either event, considerable time and expense are involved. In addition, since each piece of property, such as a television receiver, must be associated with an individual alarm system, various logistical problems are presented. The replacement of defective or obsolete television receivers with new receivers will, for example, either require the procurement of additional alarm systems for use with the new receivers or the removal of the alarms from the old receivers and the substitution thereof on the new receivers.